Underwater volcano observation by autonomous underwater vehicle "r2D4"

Based on the successes in development and field operations of AUV "R-One Robot", the Underwater Technology Research Center at the University of Tokyo established a five year project for a next generation long-range cruising type AUV from 2001, an AUV named "r2D4". The primary mission for "r2D4" is a survey of an undersea hydrothermal vent area. Construction of the hardware system as well as the primary software system were completed in July 2003. Special features of "r2D4" are the following: (1) Compact size and lightweight (length overall: 4.4 m, weight: 1,600 kg). (2) Operating max depth 4,000 m. (3) Highly accurate positioning by the combined instrumentation of fiber optic gyroscope and Doppler sonar. (4) "r2D4" has superior recognition ability on the complicated underwater environments transition by multiple sensor. (5) Adaptive path replanning ability for the observation. If the vehicle finds a suspicious place or an object in underwater space, it can regenerate the target path dynamically in order to make this observation. After the observation at Ryotsu Bay in the Sea of Japan and Kurosima knoll off Ishigaki Island, "r2D4" investigated the undersea hydrothermal vents at the area of Mariana Trough in June 2004. We succeeded in the observation of the plume from the undersea hydrothermal vents at NW Rota 1 Underwater Volcano with multiple sensor and still camera. We present the outline of the new AUV "r2D4" and the results of the survey.